Anthrax is a disease similar to diphtheria and tetanus and antibodies to anthrax protects against toxin and bacterial infections. PA was identified as a vaccine that would protect against B. anthracis infection. Further studies have shown the importance of PA as a central component for vaccine strategy. B. anthracis is fully virulent when it has protein toxin component and poly-D-glutamic acid capsule. The capsule plays an important role during initial stages of infection by preventing phagocytosis.
B. anthracis causes anthrax in animals and humans. It secretes 3 toxin components viz protective antigen (83 kDa), lethal factor and edema factor. PA is cleaved on mammalian cells by furin (in-vivo) or by trypsin (In-vitro) into 63 kDa and 20 kDa fragments. PA63 combines with lethal factor or edema factor to make lethal toxin or edema toxin, respectively. Inhibiting the PA cleavage step can abrogate anthrax toxin action. B. anthracis growth is inhibited by antibiotics but secretion of toxin makes it worse for the infected individual and can be lethal for the victim. The currently used vaccine for human consists of aluminium hydroxide adsorbed of a non-encapsulated strain of B. anthracis. Vaccine is for prevention for the onset of disease but if the person gets infected cure is not available. Antibiotics help in reducing the bacterial load but they are not effective against the toxin secreted by the bacterium. A recent report showed that a PA mutant protein inhibited anthrax toxin activity by inhibiting PA oligomerization. In present invention the inhibition of anthrax toxin activity has been shown to be inhibited a step before this, that is, by inhibiting the proteolytic cleavage of PA. Present invention therefore reports another candidate for developing a therapeutic agent that can reduce the toxic effects once the disease has set in. The invention discloses a protein molecule isolated from pollen of tropical and temperate grasses.